~~~~~~~~~~~~~~~~~~~~~~~~~~~
usim-0.91: mc6809 simulator
~~~~~~~~~~~~~~~~~~~~~~~~~~~

This is a Motorola mc6809 simulator written in C++.   

The processor simulator is implemented as a C++ class and it is
designed to be subclassed to provide virtual I/O devices and status
information.

The `mc6809' class doesn't provide any status information, but the
derived `mc6809_X' class shows processor status in an X Window.

The simple `sys' class in main.cc adds a virtual mc6850 UART by
overloading the `read' and `write' methods.

The previously released version (0.1x) had some serious bugs in the
instruction decoder but this latest version seems to run perfectly.
It successfully runs the Tiny Basic interpreter that was posted
to comp.sys.m6809 a few months ago.

v0.91 adds rudimentary support for running under DOS.  To be more
useful a minimal `conio' based terminal emulator needs to be built
into the DOS terminal handling code.

------------------------------------------------------------------------------
R. P. Bellis				E-Mail:	<Ray.Bellis@psy.ox.ac.uk>
Computing Officer
MRC Centre in Brain and Behaviour
Dept. of Experimental Psychology
University of Oxford
South Parks Road			Tel:	+44 865 271359
Oxford OX1 3UD				Fax:	+44 865 310447
------------------------------------------------------------------------------
